CINCINNATI—Twenty years after it was first used in Cincinnati’s University Hospital, a test that costs about as much as a fast-food hamburger is still helping doctors determine where a seizure in the brain takes place.
The test involves precisely calculating the time it takes to read a simple sentence—“They heard him speak on the radio last night”—during and after a seizure. When presented to patients on a laminated 8.5x11 sheet of paper, the diagnostic tool costs about $1.99.
“It helps us pinpoint where the seizures come from,” said Michael Privitera, MD, professor of neurology at the University of Cincinnati (UC) and director of the Cincinnati Epilepsy Center, part of the Neuroscience Institute at UC and University Hospital. “It’s the most cost-effective diagnostic mechanism we have for locating the source of seizures. We’ve tested 10,000 seizures this way.”
Precise localization of seizures is needed for effective surgical treatment of the thousands of people whose seizures are not controlled by medications, Privitera added.
The test, first used in 1988 and dubbed the “Cincinnati Method,” is conducted immediately following the start of a seizure to help diagnose seizure location, or seizure focus. It is used regularly in University Hospital’s Epilepsy Monitoring Unit (EMU), where patients are hospitalized over a period of days. Physicians induce seizures in patients in the EMU by temporarily withholding anti-seizure medications.
When a seizure occurs, members of the epilepsy team spring into action. After assisting the patient, a nurse or technologist presents the printed sign and instructs the patient to read out loud until the sentence is read clearly and correctly.
If the patient is unable to read, or has a specific type of speech problem called “paraphasic errors” during and following the seizure, doctors can be 90 to 95 percent certain that the seizure has occurred in the left hemisphere, the language-dominant side of the brain. Paraphasic errors occur when the patient articulates incorrect but similar-sounding words, saying “rodeo” instead of “radio,” for example, or “sproke” instead of “spoke.”
The team then reviews the seizure, which has been recorded as brain waves on an EEG (electroencephalogram), and calculates the time that elapsed from the end of the seizure to the point when the patient is able to read the words. The time delay accurately indicates that the seizure has either started from or has quickly spread to the language-dominant temporal lobe.
An early study led by Privitera found that all patients with seizures in the left temporal lobe had language delays of more than 60 seconds following a seizure’s end, while 42 of 43 patients with seizures in the right temporal lobe had a language delay of less than 60 seconds.
The simple sentence, “They heard him speak on the radio last night,” comes from the Boston Diagnostic Aphasia Test. (Aphasia is the loss of one’s ability to use or comprehend words.) The simplicity of the phrase enables nurses or technicians to detect errors easily, and memorizing it has no effect on the results.
Privitera has discussed the technique in six papers published in peer-reviewed journals, and it is used today all over the world.
Privitera and his team also use a variety of brain scans, which are significantly more expensive, to successfully determine seizure focus, including MRI (which can reveal tumors), PET, SPECT and combined EEG/fMRI.
But new does not always mean better. A new technology that accomplishes the goals of the Cincinnati Method is the magnetoencephalogram (MEG). “The MEG costs $2.6 million, plus staffing,” Privitera notes. “And its diagnostic accuracy for seizure localization is actually inferior to our own $1.99 test.
“Often new medical technology is used before the accuracy is fully tested,” Privitera continues. “We rely on a belief that if the test is really high-tech, it must be accurate. This over-reliance on high-tech even has a new name: gizmo idolatry.
“The post-seizure language testing protocol, by comparison, is not just inexpensive and simple; it has been extensively tested and is a powerful tool in our effort to determine the precise origin of seizures, which maximizes the effectiveness of treatment.”
The Neuroscience Institute at UC and University Hospital, is dedicated to patient care, research, education and the development of new treatments for stroke, brain and spinal tumors, epilepsy, traumatic brain and spinal injury, multiple sclerosis, Parkinson’s disease, Alzheimer’s disease, disorders of the senses (swallowing, voice, hearing, pain, taste and smell), and psychiatric conditions (bipolar disorder, schizophrenia and depression).
For more information about epilepsy visit www.netwellness.org, a collaborative health-information Web site staffed by Ohio physicians, nurses and allied health professionals.